THE BLOG

The powertrain describes the mechanism that generates power and propels a vehicle. Over the years, standard linear powertrains – engine, gearbox, driveshafts to wheels – have been improved to make cars more reliable, more fuel efficient, less polluting, and so on. But fine tuning one particular system can only go so far, before each adjustment puts something else out of kilter.

The real step change happens when somebody decides to work up a completely fresh system. Thanks to modern technology, the scene has been set. Enter somebody like Hugo Spowers. Hugo is founder and Company Architect at Riversimple. He is an Oxford University trained engineer who previously worked in the world of racing cars. We could also mention the bungee jumping or the piano on skis, but the focus of this blog post is the Rasa powertrain. Inspired by the Hypercar work of Amory Lovins at the Rocky Mountain Institute, the Rasa powertrain has been designed to provide everything you need and nothing you don’t in terms of power – resulting in a car that can cruise along very efficiently on a tiny fuel requirement, but can also pack a big punch when asked to accelerate or climb a hill.

Meet the Capacitors

At the heart of this car, is the hydrogen fuel cell. We describe how a fuel cell generates electrical energy from hydrogen here. But you can take the fuel cell to a whole new level with a bank of super-capacitors.

Super-capacitors in the Rasa

A capacitor is basically something that can store electrical energy. Capacitors also used to be known as condensers, used in a traditional ignition distributor. They consist of conductive plates separated by a non-conductive layer called the di-electric. When an electric current enters the capacitor, the di-electric stops the flow and a static charge builds up and is stored in an electric field between the plates. Batteries, in contrast, store electrical energy in a chemical form. This means that capacitors have some advantages over batteries: they can be charged and discharged very quickly and many times without wearing out.

But ordinary capacitors don’t hold very much charge; super-capacitors are an evolutionary leap. The prototype super-capacitors in the Rasa have a coating of charcoal and lithium ion to give them much greater capacity to hold energy – the supercap bank has a capacitance many times the capacitance of two concentric spheres the size of the planet.

Everything you need and nothing that you don’t

The unintended consequence of conventional powertrain architecture is that the engine is sized for peak acceleration, which is available all the time but is only needed for less than 10% of the time – so the car has to carry a heavy engine, and gearbox, that is 80% redundant for 90% of the time. In contrast, the Rasa powertrain will be able to recover energy that is traditionally wasted during braking, whilst allowing recaptured energy to flow precisely where it is needed, when it is needed, and for as long as is needed – but no more. There is no redundant capability, which otherwise translates into extra cost, weight and fuel consumption.

The Rasa’s Network electric powertrain

This is pretty revolutionary, and is managed by purpose-designed Riversimple software – that’s the integrated brain of the car – ensuring that:

A small, light fuel cell maintains cruise

When braking, the motors in each wheel hub recover the kinetic energy and feed it into the bank of super-capacitors

This energy stored in the super-capacitors provides most of the power (approx. 80%) required for acceleration and hill climbing

The consequence is that cruise and acceleration are ‘de-coupled’ – no longer does better acceleration unavoidably increase the top speed

As a result, the Rasa is incredibly nippy with great acceleration (and that means fun to drive), whilst the size of fuel cell and fuel tank can be kept small and light. We call it a Network Electric system.

The powertrain needs further rigorous testing and adjusting – continuing with the Beta trials – but ultimately this, coupled with the overall lightness of the design, is where groundbreaking efficiencies are being made. We anticipate that the commercial Rasa will be more than 3 times as efficient as other fuel cell cars currently on the market.

The car seats of Riversimple Rasa are a bit special. They’re covered in a durable and luxurious PET fabric that looks like suede …

… this high quality material has been manufactured from recycled plastic bottles. It’s just the kind of product choice that reflects our commitment to a supply chain fit for the 21st Century. But this isn’t just about recycling …

The Circular Economy

Ellen Macarthur first hit the headlines in 2001 when she sailed a racing yacht single-handedly around the world at just 24 years of age. Ellen says that sailing has given her a very real understanding of what it means to rely on a finite supply of resources, as on the boat food, water and fuel are inescapably linked to success or failure. Since then, Ellen has become an ambassador for the Circular Economy, focused upon the big solutions that will conserve resources for the future.

One major step is to design products that last. It’s perfectly possible, but the problem is that durable products are less compatible with business models based upon selling and selling and selling.

Dr. Stafford Lloyd joined Riversimple from Rolls Royce plc. He tells a story about his previous workplace which required the installation of high quality showers to wash off corrosive substances in case of accident. With high safety standards, such accidents were most unlikely and the showers were not expected to need replacing regularly. The manufacturers decided to lease the showers. They installed and carried out regular maintenance for a contractual fee … and business thrived.

In choosing to sell a service, the lasting qualityof a product is translated into profit.

As Systems and Sustainability Engineer at Riversimple, Stafford is on a quest to ensure that every component part of the Riversimple supply chain is of long lasting quality. A grant from Innovate UK supports his work in association with existing suppliers and specialists

and together they are developing a new business tool. This tool will be able to calculate the financial and environmental implications of sale-of-service for each supplier. Participating companies will be involved in a pilot scheme, that will be run in conjunction with the customer trial of the Riversimple Rasa. It could be a bit of a breakthrough for suppliers considering sale of service and we’ll keep you posted.

Stafford Lloyd on our Hydrogen test rig

Can I buy a RASA?

No but Rasa will be available to you one day soon we hope – through a subscription package, typically of 1 – 3 years. This will mean that

– All kinds of people will be able to choose a fuel cell car and drive away without leaving an invisible trail of pollution

– RASA subscribers won’t need to worry about the big issue of depreciation

– And RASA subscribers won’t have to worry about fuel bills, maintenance, servicing or insurance.

Which we think could be an attractive new proposition for the 21st century. Of course sustainable is possible.

We are team Riversimple. This February we are proud to present the first production prototype of a revolutionary hydrogen fuel cell car from Wales – Riversimple Rasa.

Not so long ago, Rasa looked like this.

This is the ground breaking powertrain, built in Wales.

The new car reflects a simple idea that was first mooted in the 4th century BC by the great philosopher and scientist, Aristotle. It is the idea that something new begins, not with predetermined structure and characteristics, but with a blank slate – tabula rasa – moment of potential.

We set out with a blank slate, to design a car for the world in which we now live, shaped by the best technology available to us and answerable to our most pressing concerns. We set out to build a local car that will take people on their local journeys, in the way that they wish to travel, at a cost that is affordable – and without leaving a heavy footprint of air pollution and environmental degradation. To do this we selected a still evolving, but incredibly promising and safe technology. This is hydrogen fuel cell technology.

We are a small, multi-talented, hard-working team of engineers and designers. Riversimple is headed up by company architect Hugo Spowers and supported by some big thinking business experts, without whom we would not be in this position today. As independents, we can tell you it has been no mean feat.

Riversimple Rasa is a wonder … Great to drive, safe to drive, fun to drive, light in every respect of the word, quick to refuel, and with a super strong framework of carbon fibre.

On the day that a lively crew arrived to film Rasa in action on the roads for the first time, the sun came out across the Welsh mountains – creating the perfect backdrop. At no extra cost.

Behind the excitement surrounding the forthcoming launch of the Riversimple Fuel Cell Car, are a specialised team of engineers, designers and business professionals. We are real people, working through a pivotal time for Riversimple, each with different skills and experience to bring to the table.

At the moment, everything is focused upon bringing new (disruptive) fuel cell technology to market, but the Riversimple Mk2 is part of a bigger picture – the changing requirements of day to day transport and the nature of the business model that underpins it. Riversimple’s purpose is “to pursue, systematically, the elimination of the environmental impact of personal transport”. Everything we do – the design of the car, the structure of the business, the people we work with – is in pursuit of this goal.

We have attracted some top talent

For example, Estelle Clark joined us recently to take a new business leadership role as the Steward. Continue Reading..

When you stop to think about the wide range of cars on the market today, from gas-guzzlers to electric cars, it’s clear that design choice can have an enormous effect on how much fuel the car consumes, how this will affect performance, and what impact it will have upon the environment.

We have designed the Riversimple Mk2 to be extremely fuel efficient with ultra low emissions but at the same time fun to drive and with a great range.

There is a story about the original design brief for the 2 CV. It was written in the 1930s when much of France was still rural farmland and in the brief it was stipulated that “it should be a car that you can drive across a ploughed field while it’s loaded up with trays of eggs, without breaking the eggs”. This idea touches upon something important to us all. It’s about having a car that becomes part of the way we live. At Riversimple we have been busy designing that car. We think of it as a local car.Continue Reading..

Petrol and diesel are primary fuels – you can dig them out of the ground – but if you think of hydrogen as a fuel you can make the wrong choices. In the past, some car companies invested a lot of time and money designing cars that burned hydrogen. Due to the quantity of gas required, the engineers also experimented with super-cooled liquid hydrogen, but there were numerous problems and the designs were dropped at a fairly early stage, mostly without reaching the market.

At the beginning of November, Team Riversimple were to be found at the National Exhibition Centre in Birmingham.

Riversimple at NEC. Presentation by Richard Coltart, Programme Manager, bringing the new car to production.

The annual Advanced Engineering Show has acquired an international reputation, attracting and demonstrating the latest developments in engineering. We had Riversimple’s Alpha Mk2 rolling chassis (the entire Hydrogen car minus external body shell) on show and it certainly attracted plenty of interest.

At present the design of the body shell is being kept under wraps, but from the point of view of the engineer it is the nuts and bolts of the interior that really fascinate.

This is the culmination of fifteen years development at Riversimple. Designing around hydrogen fuel cell technology has allowed us to re-invent the car for the modern world. We have four electric motors, one in each wheel and these motors are also the brakes – recovering over 50% of kinetic energy when braking. There are super-capacitors to store this energy and the recovered energy is fed back into the system to provide 80% of the power for acceleration. The primary power source is a relatively low powered hydrogen fuel cell ( 8.5 kW) housed in a beautifully constructed framework of lightweight composites.

Our overall design gives us a groundbreaking efficiency and range, many times better than inserting fuel cells into conventional, heavy, vehicles. This also means it will be agile and fun to drive, and with a massive feel good factor, as we strive towards zero cost for the environment.